Thomas Hobbes

Thomas Hobbes (1588–1679), whose current reputation rests
largely on his political philosophy, was a thinker with wide-ranging
interests. In philosophy, he defended a range of materialist,
nominalist, and empiricist views against Cartesian and Aristotelian
alternatives. In physics, his work was influential on Leibniz, and led
him into disputes with Boyle and the experimentalists of the early
Royal Society. In history, he translated Thucydides' History of
the Peloponnesian War into English, and later wrote his own
history of the Long Parliament. In mathematics he was less successful,
and is best remembered for his repeated unsuccessful attempts to square
the circle. But despite that, Hobbes was a serious and prominent
participant in the intellectual life of his time.

Thomas Hobbes was born on 5 April 1588. His home town was
Malmesbury, which is in Wiltshire, England, about 30 miles east of
Bristol. Very little is known about Hobbes's mother. His father, also
called Thomas Hobbes, was a somewhat disreputable local clergyman.
Hobbes's seventeenth-century biographer John Aubrey tells the story of
how “The old vicar Hobs was a good fellow and had been at cards
Saturday all night, and at church in his sleep he cries out
‘Trafells is troumps’” [i.e., clubs are trumps]
(Aubrey 1696, 1.387). The older Thomas Hobbes eventually (in 1604) left
Malmesbury, when a dispute with another clergyman, Richard Jeane,
escalated to the point of a fight in a churchyard. In Aubrey's words:
“Hobs stroke him and was forcd to fly for it” (Aubrey 1696,
1.387).

By that point the future philosopher Hobbes had himself left
Malmesbury (in 1602 or 1603), in order to study at Magdalen Hall,
Oxford. His studies there were supported by his uncle, Francis Hobbes,
who was a glover. After graduating from Oxford in February 1608, Hobbes
went to work for the Cavendish family, initially as a tutor to William
Cavendish (1590–1628), who later became the second earl of
Devonshire. Hobbes would work for the same family most of the rest of
his
life.[1]
His
work for the Cavendish family is part of what allowed Hobbes to think
and write as he did: it gave him access to books, and connections to
other philosophers and scientists.

Hobbes's first notable philosophical works are from around 1640.
Before then he had, significantly, published in 1629 a translation of
Thucydides' History of the Peloponnesian War into English.
Hobbes had also interacted with various prominent intellectual figures.
On a trip around Europe in the mid-1630s, Hobbes met Marin Mersenne in
Paris. Aubrey claims that “When he [Hobbes] was at Florence
… he contracted a friendship with the famous Galileo
Galilei” (Aubrey 1696, 1.366), although curiously Hobbes's
autobiographical writings do not mention this, though they do mention
meeting Mersenne. Earlier on, around 1620, Hobbes worked for some time
as a secretary to Francis Bacon.

Hobbes first made a notable impact with philosophical writings in
the early 1640s. These included his Elements of Law and De
Cive. The Elements of Law, which Hobbes circulated in
1640, is the first work in which Hobbes follows his typical systematic
pattern of starting with the workings of the mind and language, and
developing the discussion towards political matters. De Cive
(1642) was Hobbes's first published book of political philosophy. This
work focuses more narrowly on the political: its three main sections
are titled “Liberty”, “Empire” and
“Religion”. However, De Cive was conceived as part
of a larger work, the Elements of Philosophy. That work
eventually had three parts: De Corpore (1655), De
Homine (1658), and De Cive itself. De Corpore,
which is discussed below, covers issues of logic, language, method,
metaphysics, mathematics, and physics. De Homine, meanwhile,
focuses on matters of physiology and optics.

At this time Hobbes also had a series of interactions with
Descartes. In 1640 Hobbes sent to Mersenne a set of comments on
Descartes's Discourse and Optics. Descartes saw some
of this, and sent a letter to Mersenne in response, to which Hobbes
also responded. Then in 1641 Hobbes's objections were among those
published along with Descartes's Meditations. In these
exchanges and elsewhere, the attitudes of Hobbes and Descartes to one
another involved a curious mixture of respect and dismissal. On the
one occasion they are said to have met, in 1648, they did not get
along well (Martinich 1999, 171). In earlier letters, Descartes
suggested that Hobbes was more accomplished in moral philosophy than
elsewhere, but also that he had wicked views there (Descartes 1643,
3.230–1). Descartes also worried that Hobbes was “aiming
to make his reputation at my expense, and by devious means”
(Descartes 1641b, 100). Aubrey reports that the two “mutually
respected one another”, but also that Hobbes thought that
Descartes would have been better off sticking to geometry (Aubrey
1696, 1.367).

Hobbes spent the next decade in exile in Paris, leaving England late
in 1640, and not returning until 1651. His exile was related to the
civil wars of the time. Hobbes was associated with the royalist side,
and might also have had reason to fear punishment because of his
defence of absolute sovereignty in his political philosophy. During his
time in France, Hobbes continued to associate with Mersenne and his
circle, including Pierre Gassendi, who seems to have been a particular
friend of Hobbes's. Late in his time in France, Hobbes wrote
Leviathan, which was published in 1651. Its structure is
somewhat similar to that of the Elements of Law, though it
also contains lengthy discussions of matters of scriptural
interpretation, and it is probably the most overtly polemical of
Hobbes's major works.

After his return to England in 1651, Hobbes continued to publish
philosophical works for several years. De Corpore was
published in 1655, and provides Hobbes's main statements on several
topics, such as method and the workings of language. De
Homine was published in 1658, completing the plan of
the Elements of Philosophy. In later years Hobbes defended
his work in a series of extended debates. These included debates with
John Wallis and Seth Ward that centred on Hobbes's alleged squaring of
the circle (Jesseph 1999), debates with John Bramhall about liberty
and necessity (Jackson 2007), and debates with Robert Boyle about the
experimental physics of the Royal Society (Shapin & Schaffer
1989). He also published a Latin edition of Leviathan in
1668, in which there were some significant changes and additions
relating to controversial topics, such as his treatments of the
Trinity and the nature of God. But Hobbes's attention was not on
philosophy alone. Indeed, in the 1670s he published translations of
the Odyssey and Iliad. And in the late 1660s he
wrote a history of the civil wars, Behemoth; or, The Long
Parliament, which was published posthumously (Hobbes 1668a).

Hobbes died on 4 December 1679 at Hardwick Hall, one of the homes of
the Cavendish family, with whom he was still associated after seventy
years.

At an abstract level, The Elements of Law, the Elements
of Philosophy, and Leviathan all share a structure.
Hobbes begins with questions about mind and language, and works towards
questions in political philosophy. How exactly the parts of the system
are connected has long been debated. But Hobbes thinks at least that we
will better understand how individuals interact in groups if we
understand how individuals work. Thus the first part of The
Elements of Law is titled “Human Nature” and the
second “De Corpore Politico” (i.e., “About the Body
Politic”). Hobbes did not insist it was necessary to work through
all the issues about individuals before tackling the issues about
groups, as he acknowledged when he published the third part of the
Elements of Philosophy (De Cive) first. But he did
think it helpful. Thus even in Leviathan, with its focus on
political and religious matters, Hobbes starts with a story about the
workings of the mind. The first six chapters work through issues about
the senses, imagination, language, reason, knowledge, and the
passions.

Hobbes is a sort of empiricist, in that he thinks all of our ideas are
derived, directly or indirectly, from
sensation.[2]
In addition he tells a causal story about perception, which is largely
the story of a causal chain of motions. The object causes (immediately
or mediately) pressure on the sense organ, which causes motion inside
us, all the way to the “brain and heart”. And there this
motion causes “a resistance, or counter-pressure, or endeavour
of the heart to deliver itself; which endeavour,
because outward, seemeth to be some matter without. And
this seeming, or fancy, is that which men call
sense” (Hobbes 1651, 1.4). Quite why this endeavour from inside
to out should make the sensation seem to come from outside is unclear,
for things coming from outside should be moving the other way. At any
rate, the sensation is strongly grounded in, perhaps even identical
with, the internal motions. But what, we might ask, is the quality?
What is, say, red? In this chapter Hobbes seems happy to say that red
in the object is just motions in it, and that red in us is motions in
us, which give rise to or are a certain sensation. And he seems happy
to avoid the issue of whether red itself belongs to the sensation or
the object. In the Elements of Law, however, he'd been clear
about the view that colours inhere in the perceivers, not the objects
(Hobbes 1640, 1.2).

Imagination is Hobbes's next topic. His basic thought is that our
sensations remain after the act of sensing, but in a weaker way:
“after the object is removed, or the eye shut, we still retain an
image of the thing seen, though more obscure than when we see it”
(Hobbes 1651, 2.2). This is a story about how we form ideas. More
generally, imagination has a crucial role in Hobbes's picture of the
workings of the mind. One sort of imagination is what we would now call
imagination, “as when from the sight of a man at one time, and of
a horse at another, we conceive in our mind a Centaur” (Hobbes
1651, 2.4). That is, we can take the ideas, the faded sensations, from
different experiences and combine them together. But Hobbes also
connects imagination, and “the faculty of
imagining” (Hobbes 1651, 2.10) closely to memory and to
understanding. Imagination and memory, Hobbes says, are the same thing,
with two names that point to different aspects of the phenomenon of
decaying sense. If we want to point to the idea or image itself, we use
‘imagination’, but if we want to point to the decay, we use
‘memory’ (Hobbes 1651, 2.3).

Moreover, Hobbes thinks that understanding is a sort of imagination.
That is, the faculty of imagining is responsible for understanding, as
well as for compounding images and for memory. Understanding is, Hobbes
says, “[t]he imagination that is raised in man (or any other
creature endued with the faculty of imagining) by words or other
voluntary signs” (Hobbes 1651, 2.10). Understanding is not
restricted to humans. So, for example, “a dog by custom will
understand the call … of its master” (Hobbes 1651, 2.10).
But humans have a sort of understanding that other creatures lack. A
dog, for instance, can understand the will of its owner, say that its
owner wants it to sit down. In general, the understanding that
non-human animals can have is the understanding of will. But humans can
also understand the “conceptions and thoughts” (Hobbes
1651, 2.10) of others from their uses of language.

Understanding is for Hobbes the work of the faculty of imagining,
and crucially involves language. An account of the workings of language
is thus crucial for his having an account of the workings of the mind.
For Hobbes, the mind contains sense, imagination, and the workings of
language, and no further rational faculty, such as the Cartesian
immaterial mind that can grasp natures by clear and distinct
perception. His story about sensation, the formation of ideas, and the
workings of imagination is supposed to explain how some of our thought
works. But only with the further story about language and understanding
in place does he have a full alternative to Descartes's story about our
cognitive faculties. For Descartes, sense and imagination are, as in
Hobbes's story, closely connected to the workings of the brain, but
higher cognitive functions are performed by the immaterial mind. Hobbes
denies the existence of that immaterial mind, and needs other accounts
of those functions. This – combined no doubt with some
independent interest in the topic – leads to Hobbes devoting a
fair amount of attention to issues in the philosophy of language.

Hobbes's account of language is crucial for his account of the mind,
and has important connections to his views in political philosophy
(Pettit 2008). Reading Hobbes's various accounts of language, it
quickly becomes clear that the notion of signification is central. It
is apparently the central semantic relationship in Hobbes's story,
playing the sort of role that's played in more recent accounts by
meaning or sense or reference. But what is signification? One
important question here is whether and how Hobbes distinguishes
signification (and the thing signified) from naming (and the thing
named).

When Hobbes introduces his story about names in the The Elements
of Law he tells us that “A NAME or APPELLATION therefore is
the voice of a man, arbitrarily imposed, for a mark to bring to his
mind some conception concerning the thing on which it is imposed.
Things named are either the objects themselves, as man; or the
conception itself that we have of man, as shape or motion; or some
privation, which is when we conceive that there is something which we
conceive, not in him” (Hobbes 1640, 5.2–3). That is, Hobbes
first introduces names as having a private use for individuals, to help
them to bring particular ideas to mind. (Hobbes uses ‘name’
in a very broad sense. In that chapter alone, he gives
‘Socrates’, ‘Homer’, ‘man’,
‘just’, ‘valiant’, ‘strong’,
‘comely’, and ‘faith’ as example of names.)
Notice here that though the point of using names is to recall ideas,
the thing named is not necessarily an idea. It may well be an external
object such as, in Hobbes's example, a man. Later in that chapter,
Hobbes starts to talk explicitly about signifying rather than naming.
Thus in talking about ambiguity Hobbes says that “the word faith
sometimes signifieth the same with belief; sometimes it signifieth
particularly that belief which maketh a Christian; and sometimes it
signifieth the keeping of a promise” (Hobbes 1640, 5.7). However,
it is not at all clear that he really means to introduce signifying as
a relation distinct from naming here. Indeed, he seems rather to be
giving the same relation two different names.

In Leviathan and De Corpore something more complex
goes on (Duncan 2011). The equivalent chapters in Leviathan and De
Corpore start in the same way, with discussions of the role of
names as marks to aid the memory (Hobbes 1651, 4.3; Hobbes 1655, 2.1).
However, both then go straight on to introduce another role for names,
as signs to the hearer of the speaker's thoughts (Hobbes 1651, 4.3;
Hobbes 1655, 2.2–5). And ‘signify’ appears to be the
verb corresponding to what signs do. Though there are hints of this
account in Leviathan, it is set out in most detail in De
Corpore. There Hobbes says that names alone are not signs:
“they are not signs except insofar as they are arranged in speech
and are its parts” (Hobbes 1655, 2.3). So when we talk about
signification, it's the act of signifying, of communicating one's
thoughts by using words that are a sign of them, that is basic. In
other terminology, while words name things, it's utterances that have
signification.

Someone might think that, and nevertheless have a derivative notion
of what a word signifies. Hobbes takes some steps in this direction. In
particular, we can understand two words having the same signification
as their being interchangeable without changing the signification of
the utterance (Hungerland and Vick 1981, 68). Thus Hobbes uses
‘signify’ when talking about a translation relation, as
when he says in Leviathan that “the Greeks call it
fancy, which signifies appearance” (Hobbes
1651, 2.2). And some interpreters go further, and take Hobbes to
believe that words signify ideas, which are the ideas they call to mind
when used in utterances.

Hobbes is a nominalist: he believes that the only universal things
are names (Hobbes 1640, 5.6–7; Hobbes 1651, 4.6–8; Hobbes
1655, 2.9). The word ‘tree’ is, Hobbes thinks, a universal
or common name that names each of the trees. There is one name, and
there are many trees. But there is not, Hobbes argues, some further
thing that is the universal tree. Nor is there some universal idea that
is somehow of each or all of the trees. Rather, ‘tree’
names each of the trees, each of the individuals to which the term
applies (not, note, the collection of them).

What Hobbes calls common names, those words which apply to multiple
things, are applied because of similarities between those things, not
because of any relation to a universal thing or idea. There are, in the
minds of speakers, ideas related to those names, but they are not
abstract or general ideas, but individual images of individual things.
I could use ‘tree’ now, associating it with a tall pine
tree, and tomorrow use ‘tree’ but have before my mind a
short beech tree. What matters, Hobbes says, is that “we remember
that vocal sounds of this kind sometimes evoked one thing in the mind,
sometimes something else” (Hobbes 1655, 2.9).

Hobbes's nominalism was recognized by his contemporaries, but was
also criticized as going too far. Leibniz put the point as follows.

Hobbes seems to me to be a super-nominalist. For not content like
the nominalists, to reduce universals to names, he says that the truth
of things itself consists in names and what is more, that it depends on
the human will, because truth allegedly depends on the definitions of
terms, and definitions depend on the human will. This is the opinion of
a man recognized as among the most profound of our century, and as I
said, nothing can be more nominalistic than it. Yet it cannot stand. In
arithmetic, and in other disciplines as well, truths remain the same
even if notations are changed, and it does not matter whether a decimal
or a duodecimal number system is used (Leibniz 1670, 128).

Similar worries, that Hobbes's views could not account for the fact
that the same truths can be expressed in different languages, were
expressed by Descartes in his reply to Hobbes's objections to the
Meditations (Descartes 1641a, 2.126) and by Henry More in
his Immortality of the Soul (More 1659, 133–4). Hobbes would
apparently say, given his story about signification, that “This
bag is red” has the same signification as “Diese Tasche is
rot”. However, he does endorse various claims about aspects of
languge and truth being conventional and arbitrary. Some such claims
are widely agreed upon: whether we write from left to right or right
to left, for instance, and what particular marks we choose to
represent words on paper. But Hobbes also endorses other, more
controversial, claims of this sort. Most controversially perhaps,
Hobbes thinks that there is a conventionality and arbitrariness in the
way in which we divide the world up in to kinds. Though the
application of ‘red’ to some objects and not others is
based on similarities between those objects, the similarities do not
demand that we group exactly those objects together under a name. That
is, the groupings and kinds, though based in similarities, are not
determined by those similarities alone, but also and primarily by our
decisions, which involve awareness of the similarities, but also an
arbitrary element. This introduces an extra arbitrary element into the
truth of ‘This bag is red’, for even if all the underlying
similarities had been the same, we might have, say, drawn the line
between red and orange in a different place. However, it's not at all
clear that such arbitrariness gives rise to the problematic
consequences that Descartes and Leibniz think it does (Bolton
1977).

Hobbes describes reasoning as computation, and offers sketches of
the computation that he thinks is going on when we reason. This idea
might appear to have significant connections to later views, both to
some views of Leibniz's and to more recent approaches that adopt a
computational theory of mind. This section looks at Hobbes's
presentation of the idea, and then briefly at these two possible
connections to later views.

In De Corpore Hobbes first describes the view that
reasoning is computation early in chapter one. “By
reasoning”, he says “I understand computation. And to
compute is to collect the sum of many things added together at the
same time, or to know the remainder when one thing has been taken from
another. To reason therefore is the same as to add or
to subtract” (Hobbes 1655, 1.2). In the section that
follows, Hobbes gives some initial examples of addition in reasoning,
which are examples of adding ideas together to form more complex ones.
Thus “from the conceptions of a quadrilateral figure, an
equilateral figure, and a rectangular figure the conception of a square
is composed” (Hobbes 1655, 1.3). That's but a small part of our
mental activity though. Hobbes also describes propositions and
syllogisms as sorts of addition:

a syllogism is nothing other than a collection of a sum which is
made from two propositions (through a common term which is called a
middle term) conjoined to one another; and thus a syllogism is an
addition of three names, just as a proposition is of two (Hobbes 1655,
4.6).

A proposition is in a sense formed by adding the name of the predicate
to the name of the subject, so by adding ‘snow’ and
‘white’ we get ‘snow is white’. (We add
‘is’ as well, but as Hobbes argues, it's not necessary, for
we could indicate the same thing by word order rather than having an
extra word as the copula.) In thinking about syllogisms, think about
the example “Every man is an animal; every animal is a body;
therefore every man is a body” (Hobbes 1655, 4.4). In some sense
we add the propositions, or at least bits of them: we add the subject
of the first proposition to the predicate of the second, aided in this
by the middle term.

This is an intruiging suggestion, but seems not to be very far
developed. This addition has to follow some rules, especially in the
syllogistic case. As Hobbes says, “Every man is an animal; some
animal is a quadruped; therefore, some man is a quadruped” is
“defective” (Hobbes 1655, 4.4). But its conclusion too
involves the addition of parts of the premises. Presumably syllogistic
addition, like arithmetic addition, must have its rules. And of course,
Hobbes was aware of the properties of various good and bad arguments.
But it's not clear what he added to that discussion by bringing in the
language of addition. Nor, indeed, is it clear what he really added to
his discussion of the workings of the mind by his occasional use of
such language.

Nevertheless, the notion that reasoning is computation has been
referred back to more than once. Leibniz explicitly endorsed and
developed it in one early work: “Thomas Hobbes, everywhere a
profound examiner of principles, rightly stated that everything done by
our mind is a computation, by which is to be understood either
the addition of a sum or the subtraction of a difference … So
just as there are two primary signs of algebra and analytics, + and
−, in the same way there are as it were two copulas,
‘is’ and ‘is not’” (Leibniz 1666, 3). And
the idea appears to have continued to hold some appeal for him. Thus
for example Leibniz's numerical characteristic (Leibniz 1679) attempts
in another way to use the language of addition and subtraction to
explain aspects of reasoning.

Much more recently, some philosophers discussing the computational
theory of mind have also seen connections to Hobbes's idea. The central
idea of a modern computational theory of mind is that the mind is a
sort of computer. More precisely and technically, “the
immediately implementing mechanisms for intentional laws are
computational … [Computations] viewed in intension, are
mappings from symbols under syntactic description to symbols under
syntactic description” (Fodor 1994, 8). And very roughly, we
might see Hobbes as saying the same thing. There are various mental
processes (compounding ideas, forming propositions, reasoning
syllogistically) that we can describe without knowing that reasoning is
computation. But the underlying process that's making this all work is
computation, namely, addition and subtraction. The connections seem to
amount to no more than that though, so it's at least rather
over-dramatic to say that Hobbes was “prophetically launching
Artificial Intelligence” (Haugeland 1985, 23).

By the time of Leviathan and De Corpore, Hobbes
was convinced that human beings (including their minds) were entirely
material.[3]
Later
on he came to think that even God was a sort of material being (Gorham
2013, Springborg 2012). This section focuses on Hobbes's materialism
about human beings. This was not a popular or widely-held position at
the time. Hobbes, however, was a materialist. Why was he a
materialist?

We might suspect that Hobbes's story about the workings of mind and
language (e.g., in the early chapters of Leviathan) is
supposed to be an implicit argument for materialism.
‘Look’, we might take Hobbes to be saying, ‘I can
explain all the workings of the mind using only material resources.
What need is there to postulate an immaterial mind when this perfectly
good, and more minimal, explanation is available?’ Hobbes perhaps
suggests this when he notes that his nominalism means we do not need to
suppose there's any faculty other than imagination in order to
understand how universal thought works (Hobbes 1655, 2.9). However, for
the most part we do not find Hobbes explicitly stating that argument.
Instead he presents a series of arguments against various opponents'
beliefs in immaterial beings (including immaterial human minds).

Most prominent in Leviathan is an argument that talk about
incorporeal things is “insignificant speech”.

All other names are but insignificant sounds; and those of two
sorts. One when they are new, and yet their meaning not explained by
definition; whereof there have been abundance coined by schoolmen, and
puzzled philosophers.

Another, when men make a name of two names, whose significations are
contradictory and inconsistent; as this name, an incorporeal
body, or (which is all one) an incorporeal
substance, and a great number more. For whensoever any affirmation
is false, the two names of which it is composed, put together and made
one, signify nothing at all (Hobbes 1655, 4.20–1).

Thus Hobbes apparently thinks that talk about incorporeal substances
(such as Cartesian unextended thinking things) is just nonsense. But
why does he think that? Hobbes's comment about false affirmations
suggests he thinks that ‘incorporeal substance’ is
insignificant because ‘a substance is incorporeal’ is
false. But that seems to derive the insignificance from the truth of
materialism, which is hardly going to convince Hobbes's opponents.
Hobbes does offer a supporting argument, when he claims that
‘incorporeal substance’ and ‘incorporeal body’
are “all one”. But that premise too will be denied by his
opponents, who think that there can be substances that are not bodies,
and that ‘substance’ and ‘body’ are far from
interchangeable terms.

Hobbes offers a further argument against his opponents' belief in
immaterial things in De Corpore, in a passage in which he
talks at length about the “gross errors” of
philosophers.

But the abuse consists in this, that when some men see that the
increases and decreases of quantity, heat, and other accidents can be
considered, that is, submitted to reasons, as we say, without
consideration of bodies or their subjects (which is called
“abstraction” or “existence apart from them”),
they talk about accidents as if they could be separated from every
body. The gross errors of certain metaphysicians take their origin from
this; for from the fact that it is possible to consider thinking
without considering body, they infer that there is no need for a
thinking body; and from the fact that it is possible to consider
quantity without considering body, they also think that quantity can
exist without body and body without quantity, so that a quantitative
body is made only after quantity has been added to a body. These
meaningless vocal sounds, “abstract substances,”
“separated essence,” and other similar ones, spring from
the same fountain (Hobbes 1655, 3.4).

The key mistake, Hobbes thinks, lies in moving from the observations
that we can talk about ‘A’ and ‘B’, and can
think about A without thinking about B, to the conclusion that A can
exist without B existing. Hobbes attacks various views associated with
the Scholastic Aristotelian tradition as resting on that mistake. One
aim of this critical passage is to support materialism by showing a
problem with the belief that there can be thought without a body.
Hobbes elsewhere claims that Aristotle thinks that “the human
soul, separated from man, subsists by itself”, so presumably has
Aristotle and Aristotelians in mind as targets (Hobbes 1668b,
46.17).

When Hobbes talks about Aristotelian views, one might ask whether
his target is Aristotle himself, or some later Aristotelians. When
Hobbes talks about Aristotelian metaphysics in particular, his main
approach seems to be to take a certain core view to have been
Aristotle's, then to criticize both that view and the further uses that
were made of it. Hobbes's attitude to Aristotelianism comes across
forcefully in a discussion in Behemoth that begins by
describing Peter Lombard and John Duns Scotus as writing like “two
of the most egregious blockheads in the world” (Hobbes 1668a,
41–2). That exchange has several elements: the condemnation of the
philosophical view as nonsensical; the claim that some philosophers aim
to confuse; and the claim that views are promoted in order to control
the public and take their money. However, though Hobbes rejected a good
many of the views of the Scholastic Aristotelian tradition, his work
nevertheless had a good many connections to it, as is illustrated by
Leijenhorst 2002.

The view that there can be thought without a body is also
Descartes's view. Indeed, Hobbes may be thinking of Descartes's
argument for that view in the Sixth Meditation. A key claim in
Descartes's argument is that “the fact that I can clearly and
distinctly understand one thing apart from another is enough to make me
certain that the two things are distinct” (Descartes 1641a,
2.54). Descartes argues, via that claim, from his ability to clearly
and distinctly conceive of mind apart from body and vice versa, to the
conclusion that mind and body are really distinct (i.e., are two
substances, not one). Abstracting away from the details, we have an
argument from the conceivability of mind without body to the conclusion
that the mind is not physical. And such an argument is one of Hobbes's
targets in the “gross errors” passage.

However Descartes, by endorsing that argument, does not endorse the
claim that ‘if I can conceive of A's existing without B's
existing, then A can exist without B existing’. He endorses at
most the weaker claim that ‘if I can clearly and distinctly
conceive of A's existing without B existing, then B can exist without A
existing’. There's a special sort of conceivability involved
here, clear and distinct conceivability, which licenses the move in
this case but not in general. Hobbes's argument seems blind to this
distinction.

Overall then, something of a puzzle remains. Hobbes clearly was a
materialist about the natural world, but the explicit arguments he
offers for the view seem rather weak. Perhaps he just had a good deal
of confidence in the ability of the rapidly developing science of the
his time to proceed towards a full material explanation of the mind.
Just as his contemporary William Harvey, of whom he thought very
highly, had made such progress in explaining biological matters, so too
(Hobbes might have thought) might we expect further scientists to
succeed in explaining mental matters.

At any rate, Hobbes was very much interested in scientific
explanation of the world: both its practice (which he saw himself as
engaged in) and also its theory. Chapter 9 of Leviathan tells
us something about the differences between scientific and historical
knowledge, and the divisions between sciences. Chapter 6 of De
Corpore gives a much fuller treatment of issues in the philosophy
of science, issues of what Hobbes calls method. Method tells us how to
investigate things in order to achieve scientia, the best sort
of knowledge.

Those writing about Hobbes's method have tended to tell one or other
of two stories about the sort of method he proposes and its historical
roots. One story emphasizes the connections between Hobbes's method and
Aristotelian approaches. This has often been developed into a story
about the particular influence on Hobbes of the works of Giacomo
Zabarella, a sixteenth-century Aristotelian who studied and taught at
the University of Padua, which influence is then often said to have
been somehow mediated by Galileo. The alternative story emphasizes the
connections between Hobbes's general views about method and the
traditions of thinking about method in geometry. Here the notions of
analysis and synthesis are key. Oddly enough, both of these stories can
be connected to anecdotes that Aubrey tells about Hobbes: on the one
hand, the report that Hobbes because friendly with Galileo while
traveling in Italy, and on the other, the tale of how Hobbes became
fascinated with geometry at the age of forty after looking at copy of
Euclid's Elements, not believing a proposition, and tracing
back the demonstration of it and the propositions on which it
depended.

This section tells a version of the first story (for criticism of
such an approach, see Prins 1990). Still, one should note that Hobbes
sometimes uses the language of mathematical method, of analysis and
synthesis, in describing his general method (Hobbes 1655, 6.1). Several
commentators have seen this, together with his clear admiration for the
successes of geometry, as evidence of a more general use of
mathematical notions in his account of method (Talaska 1988.) And it
might indeed be the case that both stories about Hobbes's method (the
Zabarellan and the mathematical) have some truth to them.

Those writing about Hobbes often describe Zabarella's method as
having two parts, resolution and composition. Resolution moves from the
thing to be explained, which is an effect, to its causes, and then
composition brings you back from causes to effects. At a suitably
general level that is correct, but it misses much detail. Most
importantly, Zabarella's method — as seen for instance in his
work De Regressu – is better described as having three
parts. A crucial though somewhat third mysterious step stands between
the move from effect to cause and that from effect to cause. The
complete sequence, the arguments from effect to cause and back again,
Zabarella calls regressus. This sequence improves our
knowledge, taking us from confused to clear knowledge of something. But
how do we do this? The first step is to move from having confused
knowledge of the effect to having confused knowledge of the cause.
Roughly, you need to figure out what caused the thing you're trying to
explain. The second step moves from confused to clear knowledge of the
cause. This step works, Zabarella thinks, by a sort of intellectual
examination of the cause. The aim is not just to know what thing is the
cause, but to understand that thing. The final step then moves from the
clear knowledge of the cause to clear knowledge of the effect. That is,
your new full understanding of the cause gives you better understanding
of the thing caused by it.

Chapter six of De Corpore is Hobbes's main work on method.
There Hobbes lays out a model of the proper form of a scientific
explanation. A proper explanation tells you three things: what the
cause is, the nature of the cause, and how the cause gives rise to the
effect. Thus Hobbes accepts the Aristotelian idea that to have the best
sort of knowledge, scientific knowledge, is to know something through
its causes. Similarities to Aristotelian theories such as Zabarella's
show up even in section one of chapter six. Here Hobbes defines
philosophy as knowledge acquired by correct reasoning. It is both
knowledge of effects that you get through conception of their causes
and knowledge of causes that you get through conception of their
visible effects. Already we see signs of the Aristotelian picture in
which you come to know the cause by knowing the visible effect and to
know the effect by knowing the cause.

Moreover, there is in Hobbes's method something like the middle step
of regressus. For Hobbes, to know an effect through its causes
is to know what the causes are and how they work: “We are said
to know scientifically some effect when we know what its
causes are, in what subject they are, in what subject they introduce the
effect, and how they do it” (Hobbes 1655, 6.1). The
requirement to know how the cause works, not just what it is, is
analogous to the Zabarellan requirement to have distinct knowledge of a
cause. Knowledge that the cause exists comes from the first step of
regressus. Complete regressus, i.e., complete
explanation, requires that you make a fuller investigation of the
cause. For Hobbes, analogously, to get to scientia of the
effect you need to understand, not just what the causes are, but how
they work.

Comparison of Hobbes's view to Zabarella's and other more fully
Aristotelian ones is complicated by Hobbes's thinking that all causes
are efficient causes and that motion is the cause of all change in the
natural world. In a more fully Aristotelian picture, explanations are
causal, but causes can be of several sorts. Hobbes's picture is more
restrictive: to find the causes is to find the efficient causes.
Moreover, he thinks the efficient causes are all motions, so the search
for causes becomes the search for motions and mechanisms.

For all that there do seem to be similarities between Hobbes's
method and older Aristotelian approaches, one might well wonder how
Hobbes could have come to know about Zabarella's views in particular.
One story is that Hobbes learned about this method from Galileo, but
that claim is problematic. Galileo did know about Zabarella's ideas and
other similar ones (Wallace 1984). However, the texts of Galileo in
which signs of Zabarellan ideas are evident are early ones, but Hobbes
knew Galileo's thought through his later published works. But even if
the Zabarella-Galileo-Hobbes story is hard to support, there are other
ways in which Hobbes might have learned of Zabarella's work. Harvey,
whose work Hobbes greatly admired, and who studied at the medical
school in Padua, might also have been an intermediary (Watkins 1973,
41–2). And it's far from ridiculous to contemplate Hobbes reading
the work of the popular logician Zabarella.

Hobbes's views about religion have been disputed at great length,
and a wide range of positions have been attributed to him, from atheism
to orthodox Christianity. This section focuses on two central
questions: whether Hobbes believes in the existence of God, and whether
he thinks there can be knowledge from revelation. Some important
aspects of Hobbes's approach to religion are left aside. These include
religion's role in politics (Lloyd 1992), and the question of whether
God plays some fundamental role in Hobbes's ethical system (see
Warrender 1957 and Martinich 1992, but also Nagel 1959 and Darwall
1994).

Hobbes at one point rules a good deal of religious discussion out of
philosophy, because its topics are not susceptible to the full detailed
causal explanation that is required for scientia, the best
sort of knowledge. “Thus philosophy excludes from itself
theology, as I call the doctrine about the nature and attributes of the
eternal, ungenerable, and incomprehensible God, and in whom no
composition and no division can be established and no generation can be
understood” (Hobbes 1655, 1.8). Also excluded are discussion of
angels, of revelation, and of the proper worship of God. But despite
these not being, strictly speaking, philosophy, Hobbes does in fact
have a good deal to say about them, most notably in Leviathan.
Things outside philosophy (in its strict sense) may not be amenable to
thorough causal explanation in terms of the motions of bodies, but they
may well still be within the limits of rational discussion.

Many people have called Hobbes an atheist, both during his lifetime
and more recently. However, the word ‘atheist’ did not mean
the same thing in the seventeenth century as it meant now. Thus when
Mintz (1962), in a study of Hobbes's critics that often mentions
atheism, summarizes the reasons those critics gave for calling Hobbes
an atheist, he lists the views

that the universe is body, that God is part of the world and
therefore body, that the Pentateuch and many other books of Scripture
are redactions or compilations from earlier sources, that the members
of the Trinity are Moses, Jesus, and the Apostles, that few if any
miracles can be credited after the Testamental period, that no persons
deserve the name of ‘martyr’ expect those who witnessed the
ascension of Christ, that witchcraft is a myth and heaven a delusion,
that religion is in fact so muddled with superstition as to be in many
vital places indistinguishable from it, [and] that the Church, both in
its government and its doctrine, must submit to the dictates of
Leviathan, the supreme civil authority (Mintz 1962, 45).

Thus, many of Hobbes's critics in the seventeenth century, including
those who vehemently attacked his religious views, still thought he
believed in the existence of God. They thought, however, that he was a
rather dubious sort of Christian. Other critics, however, have thought
that Hobbes in fact denied the existence of God. This might seem a
curious allegation, for Hobbes often talks about God as existing.
Certainly, to read Hobbes in this way requires one to take some of his
statements at something other than face value.

In the Elements of Law Hobbes offers a cosmological
argument for the existence of God (Hobbes 1640, 11.2). However, he
argues, the only thing we can know about God is that he, “first
cause of all causes”, exists. Our knowledge is limited in this
way because our thoughts about God are limited: “we can have no
conception or image of the Deity”. So when we seem to attribute
features to God, we cannot literally be describing God (Hobbes 1640,
11.3). We're either expressing our inability, as when we call God
incomprehensible, or we're expressing our reverence, as when we call
God omniscient and just. The same indeed is going on when we call God a
spirit: this is not “a name of anything we conceive”, but
again a “signification of our reverence” (Hobbes 1640,
11.3).

Those three views — support for a cosmological argument, the
belief that God is inconceivable by us, and the interpretation of
apparent descriptions of God as not really descriptions — appear
to recur in Leviathan (Hobbes 1651, 11.25, 12.6–9).
However, in later work, such as the appendix to the 1668 Latin edition
of Leviathan, Hobbes proposes a different view. The older
Hobbes thought that we could know God to have at least one feature,
namely extension. In his Answer to Bishop Bramhall, Hobbes
describes God as a “corporeal spirit” (Hobbes 1662, 4.306).
By this he means at least that God is extended. Indeed, Hobbes seems to
think of God as a sort of extended thing that's mixed through the rest
of the world, not being in every individual place in the world, but
able to affect all the things in the world (Hobbes 1662,
4.306–13, especially 4.309–10).

Whatever one thinks of the orthodoxy of Hobbes's earlier views
— and one might take the holder of those views just to be a very
serious believer in the rather orthodox view that God is
incomprehensible — this later view that God is corporeal is
strange indeed. However, Hobbes does seem in his Answer to Bishop
Bramhall and the Appendix to the Latin edition of
Leviathan to believe this strange view sincerely. Indeed, he
goes to some pains to defend this as an acceptable version of
Christianity. Whether or not one believes that, this is still on the
surface an odd theism rather than atheism.

Even if Hobbes is some sort of theist, he's a theist who is
sceptical about many widely held religious views. This is notable to
some extent in his critical reading of biblical texts, which was not at
all a standard approach at the time. Indeed, Hobbes and Spinoza often
get a good deal of credit for developing this approach. It's notable
too in his treatment of matters related to revelation.

In chapter 2 of Leviathan Hobbes comes to these topics at a
slightly surprising point. In the course of discussing the workings of
imagination, he talks naturally enough about dreams. Emphasizing the
occasional difficulty of distinguishing dreams from waking life, he
turns to talk of visions. Dreams had in stressful circumstances, when
one sleeps briefly, are sometimes taken as visions, Hobbes says. He
uses this to explain a supposed vision had by Marcus Brutus, and also
widespread belief in ghosts, goblins, and the like. Later he uses it to
account for visions of God (Hobbes 1651, 32.6). And Hobbes explicitly
uses this to undermine the plausibility of claims to know things
because told by God:

To say he [God] hath spoken to him in a dream is no more than to say
that he dreamed God spake to him, which is not of force to win belief
from any man that knows dreams are for the most part natural and may
proceed from former thoughts … To say he hath seen a vision, or
heard a voice, is to say that he hath dreamed between sleeping and
waking; for in such a manner a man doth many times naturally take his
dream for a vision, as not having well observed his own slumbering
(Hobbes 1651, 32.6)

This does not rule out the possibility that God might indeed
communicate directly with an individual by means of a vision. But it
does rule out other people sensibly believing reports of such
occurrences, for the events reported are easily (and usually if not
necessarily always correctly) given a natural explanation as dreams,
which themselves have natural causes.

Hobbes takes a similarly sceptical attitude to reports of miracles.
Chapter 37 of Leviathan is a discussion of this topic, centred
on Hobbes's definition of a miracle as “a work of God
(besides his operation by the way of nature, ordained in the creation),
done for the making manifest to his elect the mission of an
extraordinary minister for their salvation” (Hobbes 1651,
37.7). Though there is some dispute about exactly what Hobbes is doing
there, there clearly is a good deal of talk about “false”
or “pretended” miracles, with an emphasis on the
possibility of trickery, and a warning about believing too hastily in
reports of miracles. The conclusion is weaker than that of Hume's more
famous argument about the evidence for belief in miracles, but a
similar sceptical attitude is present.

The case has often been made, however, that Hobbes was not just
somewhat sceptical about some religious claims, but actually denied the
existence of God. The idea is that, though Hobbes says that God
exists, those statements are just cover for his atheism. Moreover,
these interpreters claim, there are various pieces of evidence that
point to this hidden underlying view. Opinions differ on what the
crucial evidence of the hidden atheism is. Jesseph (2002), for
instance, argues that Hobbes's claims about a material God do not add
up. Curley (1992) argues that Hobbes's discussions of prophecy and
miracles, taken together, contain a suggestive problem.

There is (what I would take to be) a fairly obvious problem of
circularity here: in the chapter on miracles we are to judge the
authenticity of a miracle by the authenticity of the doctrine it is
used to support, but in the chapter on prophecy we had to judge the
prophet's claim to be God's spokesman by his performance of miracles.
If Hobbes is aware of this circularity, he does not call attention to
it. Perhaps he just did not notice it. Perhaps, as Strauss might have
suggested, he leaves it to the reader to discover this for himself.
(Curley 1992, §5).

There are some tricky general methodological questions here, about
when we can reasonably say that an author is trying to communicate a
view other than the one apparently stated. Note, however, that for
someone allegedly covering up his atheism to avoid controversy, Hobbes
took the curious approach of saying many other intensely controversial
things. He was opposed to free will and to immaterial souls, opposed to
Presbyterianism and to Roman Catholicism, and managed to have
anti-royalists thinking he was a royalist, but at least one prominent
royalist (Clarendon) thinking he supported Cromwell. This was not a
recipe for a quiet life. One might see Hobbes as thinking that these
things could be said with controversy, but God's existence only denied
with genuine danger. But one needs, at least, a fairly complex story
about Hobbes's attitudes in order to sustain the view that he was
sneakily suggesting that God didn't exist.

Hobbes was a widely read and controversial author. In many cases,
the discussion that ensued about his philosophy was about his political
philosophy (Goldie 1994, Malcolm 2002). However, Hobbes's non-political
views were also discussed. The Cambridge Platonist Ralph Cudworth, for
example, devoted considerable energy to arguing against Hobbesian
atheism and materialism. One important connection is that between
Hobbes's work and Leibniz's. Of all the canonical philosophers in the
period from Descartes to Kant, Leibniz is probably the one who paid
most attention to Hobbes's work, and had the most to say about
different aspects of it. Leibniz found Hobbes's work worthy of serious
engagement, but ultimately also thought it mistaken in many ways. On
the other hand, later empiricist philosophers, in particular Locke and
Hume, develop several Hobbesian themes. Indeed, one might well speak of
Hobbes, not Locke, as the first of the British empiricists.

The best known parts of Leibniz's interaction with Hobbes are from
early in Leibniz's philosophical career, before 1686, the year in which
Leibniz wrote his ‘Discourse on Metaphysics’ (Bernstein
1980; Jesseph 1998; Moll 1996, 103–36; Wilson 1997). His criticism of
Hobbes's nominalism, and his early adoption of the view that reasoning
is computation, were both discussed above. Leibniz also paid a good
deal of attention to Hobbes's views about motion, in particular those
about conatus or endeavour, which have application both to
physics and to mathematics. And Leibniz twice in the 1670s wrote
letters to Hobbes, though it is unclear if Hobbes ever received them,
and there is no evidence of any replies. Leibniz continued, moreover,
to engage with Hobbes's work throughout his philosophical career, even if
that engagement was never quite as intense as it was in a brief early
period. There is, for instance, a discussion of Hobbes's views in the
1709 Theodicy.

Looking beyond Leibniz, we can see some close connections between
the work of Hobbes and the work of Locke and Hume, both of whom were
well aware of Hobbes's views. Locke's connections to Hobbes, though
perhaps not obvious, are there (Rogers 1988). Think of Locke's
empiricism (i.e., anti-nativism), his attention to language and its
workings and related errors, his granting at least the possibility of
materialism being true, and his scepticism about revelation. Hume,
meanwhile, begins his Treatise with his view about ideas being
less intense copies of our sensations, a view with a close resemblance
to Hobbes's view about decaying sense. Russell (1985; 2008) argues
convincingly that Hume modelled the structure of the Treatise
on that of Hobbes's Elements of Law. And Hume, like Hobbes,
combines apparent acceptance of a basic cosmological argument with
scepticism about many religious claims. Indeed there are enough
connections that it's plausible to speak of “the empiricism of
Hobbes…, Locke…, and Hume” (Nidditch 1975, viii),
rather than of the more conventional trio of Locke, Berkeley, and
Hume..

Though the vast majority of work on Hobbes looks at his political
philosophy, there are general books on Hobbes that look at his
non-political philosophy, such as Sorell 1986 and Martinich 2005. The
best modern biography is Martinich 1999.

References to The Elements of Law, Leviathan, and
De Corpore are by chapter and paragraph number. This should
enable readers to find references in editions other than the ones used
here (even though most editions of Leviathan do not print
paragraph numbers). All other references are given by volume and page
number. Most works are referred to using their author's name and their
date of first publication. A few others — Hobbes's Elements
of Law and Behemoth, Aubrey's Brief Lives, and
some works of Leibniz — are referred to using their dates of
composition, because they were published several years after they were
written.

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